Record $5.5m payment 'not enough' for cop

The family of a West Australian policeman left paralysed after contracting a rare disease says his lifetime of care will cost more than double the record $5.5 million ex-gratia payment he was offered.

Constable Ryan Marron became ill with the mosquito-borne disease Murray Valley encephalitis while working in the remote Balgo community in the Kimberley in 2011.

His father, Tom Marron, said the family was grateful for the payment but had sought $12 million, plus trustee fees, with more than $6.5 million of that sum needed just for care services.

Mr Marron and his wife currently help care for their son but it is taking a toll, he says.

"He's cognitively 100 per cent and of course it gets him down," Mr Marron told reporters.

"He can't walk, he can't talk, he can't feed himself, he can't go to the toilet.

"To be one minute a six-foot-three, 90kg police officer to what he is now, yeah that does get him down."

While there was no one to blame for what happened, his son was an employee of the government and deserved fair payment, Mr Marron said.

Const Marron also has the support of opposition leader Mark McGowan and WA Police Union president George Tilbury, who said the offer was inadequate and the government should be ashamed.

But Attorney General Michael Mischin said the ex-gratia payment was fair and in addition to the $400,000 the state government gave in 2012 to help Const Marron seek specialist medical treatment in the US.

Mr Mischin stressed the payment was not compensation and Const Marron was still entitled to assistance from other government-funded agencies.

Asked whether the public trustee should cover the fees on a pro bono basis, Mr Mischin said it would be a "fine thing", but the costs would have to be absorbed by others and it was up to the trustee.

While corporate trustee fees would be considerable, only a small amount was paid up front and the funds would be invested and generate significant income similar to superannuation, he said.

Police Commissioner Karl O'Callaghan said Const Marron would remain on the payroll until the matter was resolved.

WA is the only state without a worker's compensation scheme for police, prompting Mr O'Callaghan to renew calls for one.